(a) Field of the Invention
The present invention relates to a contact portion of semiconductor device and a method for manufacturing the same, and a thin film transistor array panel for display device including the contact portion and the method for manufacturing the same.
(b) Description of the Related Art
In general, it is preferable that, as a semiconductor device is more integrated, an area of the device is optimized and a wiring thereof is made of multi-layers. In this case, preferably, an interlayer insulating film is made of material with a low dielectric constant in order to minimize an interference of signals transferred through the wiring, and the wiring transferring the same signals has to be connected electrically by forming a contact hole in an insulating film. However, if an under-cut is generated on the contact portion on forming the contact hole by etching the insulating film, a step coverage of the contact portion becomes bad. This causes a problem that a profile of the wiring formed on the insulating film becomes bad or the wiring in the contact portion is disconnected.
In the meanwhile, a liquid crystal display (LCD) is one of plat panel display devices which are used most widely, and it is a display device that comprises two substrates on which electrodes are formed and a liquid crystal layer interposed therebetween, and that applying the electrodes makes the liquid crystal molecules in the liquid crystal layer rearranged, thereby adjusting amount of the light transmitted.
The mainly used LCDs are those that electrodes are formed on two substrates respectively and have a thin film transistor switching voltages applied to the electrodes.
In general, on the substrate where a thin film transistor is formed, wire including gate lines transmitting scanning signals and data lines transmitting data signals, and a gate pad and a data pad applied with the scanning signals and data lines from external devices to transmit the gate lines and the data lines respectively, are formed, and pixel electrodes electrically connected with the thin film transistor are formed on pixel areas defined by crossing the gate lines and the data lines.
Here, it is preferable that an aperture rate of the pixel is sure to be obtained in order to improve display features of the LCDs. For this, the wire and the pixel electrodes are made to overlap with each other, an insulating film made of organic material with a low dielectric constant is formed therebetween in order to minimize interferences of signals transmitted through the wire.
This method for manufacturing the thin film transistor array substrate for display device requires a process that exposes a pad for receiving signals from external devices or a process that exposes wire in order to be connected with each other. However, when a lower film is etched to form a contact hole thereon by using an insulating film having the contact hole as a mask, the lower film beneath the insulating film is severely under-cutted, and hence the step coverage of the contact portion becomes bad. This causes problems that the other upper films formed later become bad or the wire of the upper films are disconnected on the contact portion. To solve these problems, it is preferable that sidewalls of the contact holes in the contact portion are made to be step-shaped, however, since the organic insulating film must be patterned several times by a photo etching for this, it has a problems that its manufacturing process becomes complex.
In the meanwhile, a seal line attaching two substrates around the LCD panel and sealing liquid crystal material posed therebetween is formed, and a poor contact is generated if this seal line is formed on the organic insulating film.